I'm looking to be able to run some serious programs, a lot of business function like microsoft project, vizio, catia, adobe suite 3.0, etc. I will also be playing some games like crysis, far cry 2, cod 5, cs:s, starcraft 2, etc.

The main reason for this build is, my last computer couldn't run these programs well, and had serious trouble launching stuff like dreamweaver and I had a athlon 3800+ with a couple gigs of ddr ram.

I will be running my company off this computer for a while until I can afford to have more than 2 systems. (have laptops now).

First off, the Core i7 is a SERVER cpu made into a desktop application. With that, its one fucking beast. Its computing power is top dog right now. But for those who are looking to upgrade for gaming, might not be worth the upgrade right now because its a very expensive move and the gains are very minimal. Also, the cheapest motherboard is $200+ and is based off the X58 chipset. Plus, the DDR3 is clearly much much more expensive than DDR2. Anyway, here are the pros and cons:

Pros:
-Very very fast for multimedia encoding, photoshop, etc... The type of program you are looking into.
-Supports hyper-threading (good for a couple of %s in some apps)
-QPI (eliminating FSB and integrating mem. controller to cpu).
-Turbo boost (like vtec but only if overclocking is disabled).
-Triple channel RAM
-Increased power efficiency over Core2.
-Overclocks just as well as Core2.

Cons:
-Very expensive.
-Runs very hot
-Little FPS gain for gamers.
-When overclocking, have to be very careful with high VDimm or your cpu WILL DIE.

With those mentioned, I think in your case its easily appealing. Just the motherboards are really really expensive and their BIOS need much tweaking, especially if you plan load mem. slots. For the RAM, 3GB seems kinda silly because most people are running at least 4GB for the apps you intend to run and in x64 form, but again DDR3 is 4x more than DDR2. Hopefully DDR3 prices will drop because i7 likes the higher speed RAM.

So you have a couple of options. A) Wait till platform matures and prices of components come down. B) Building a cheapy Core2 system and upgrade to i7. C) Take the jump and get i7 now. If you do a lot of dreamweaver and such, i would choose C.

I'm looking for longetivity and bang for the buck. I understand the mobo and ram are expensive, but, a properly built core 2 is around 400 less, and won't be upgradable really much longer as its maturing-> moving to extinction in terms of new processors, hardware etc coming out based on those systems.

thats almost a $500 premimum over building your own. and in terms of best bang for buck, its hard to argue with core2 because its much more mature and cheaper. i7 costs two times as much but doesnt offer 2x the performance. and the only difference between hardware of the two is the change in cpu because there are core2 boards that use ddr3 and everything else i7 does. also, there is no such thing as upgrade proof in computers, especially when intel is doing their tick tock model with every 2-3 years, there will be a new architecture. thusly, buy what you can afford and need. if you feel money is more important, the core2 is hard to beat. but if performance is more important, that extra speed will reduce waiting times and time is money. and just as a side note, nehalem will have mainstream parts that will have a different socket than higher models.